Interesting Speculation on Teratorns

A very quick doodle (15 minutes) of a teratorn swallowing a bone, because I couldn´t sleep last night and this came to my mind… what if teratorns were bone-eating specialists? Bear with me.

Originally imagined as giant vultures, and depicted as such, teratorns were large carnivorous birds that inhabited the Americas during the late Cenozoic, and went extinct at the same time as the megafauna at the end of the Pleistocene/beginning of the Holocene. They were huge, with wingspans estimated at 3 to 5 m (the very largest, Argentavis, has been estimated at 6-7 m even, but its size might have been overestimated).

Their remains often show up in fossil sites that used to be natural death traps, such as tar pits and caves, along with those of vultures and condors. This is why it’s long been assumed they were scavengers, that were attracted by the trapped, dead or dying beasts and became entrapped themselves.

Thing is, teratorns have some curious traits. For example, their beak is not what you’d expect from a bird that lives by tearing flesh from large carcasses, like vultures do. Instead, it is low and long and the skull is very kinetic suggesting it had a very large gape. The legs were robust and they had pelvis adaptations that allowed them to walk on land more efficiently than vultures and other raptors, but the range of motion of the legs was not as extreme as in eagles or hawks, and it lacked the long raptorial talons of these, so it was not snatching prey from the air. It has been suggested recently that teratorns lived a bit like caracara, spending much time on the ground and hunting smkall animals (up to rabbit or hare size) on foot, then swallowing them whole.

There is however a weird trait that seems to contradict the idea of an active hunter; its eyes were proportionally small and directed more to the sides of the head than in “regular” raptors, so it didn´t have great binocular vision. Whatever it was doing, it did not require it. So, what was it doing?

Hereby I, sleepless artist absolutely lacking in scientific credentials, propose that teratorns were bone specialists, a bit like today’s lammergeier or bearded vulture. Today, its niche seems like a rarity to us, but only because we live in a world depleted of its megafauna. In prehistoric times the landscape would be constantly littered with the remains of great beasts. Teratorns, with their wide fields of vision, would have monitored vultures and condors and follow their movements to their eventual food sources. Instead of competing with them, they’d patiently wait until the carcass was stripped of the meat and carnivores lost interest. Then they would have the skeleton for themselves and maybe could live off it for quite a while. Enter the beaks that weren´t meant for tearing flesh and the wide gape to swallow decent sized bones whole and pieces of larger ones; it may have broken the larger bones by striking them on the ground or dropping them from the air, again like lammergeier. The teratorn’s large size would allow it to carry, break and consume large bones so very little of the skeleton would go to waste.

And again, the wide vision field allowed them to watch their surroundings while busy “working” on a skeleton on the ground, in case a curious predator got too close. The strong legs would help it work at the skeleton pulling, breaking and carrying the bones but also walk and run efficiently, either for escaping land predators or to collect bones scattered over a large area.

This would all explain why teratorns went extinct along with the megafauna (which wouldn´t be the case if they fed on small mammals), and also how they managed to coexist with so many vultures and condors without competing with them. It’s just I don´t think birds this big are ideal for hunting quick small mammals like rabbits or hares; instead, as bone eaters, they’d have a whole niche only for themselves.

by Hodari Nundu

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Three flying giants from different time periods

Quetzalcoatlus from the Mesozoic, Argentavis from the Cenozoic and Meganeuropsis from the Paleozoic.

by Fabio Alejandro